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Given the following scenario:

[...] The refueling is terminated either when the maximal permissible amount of petrol is dispensed, or when the customer decides to put the hose back into the mounting plate. The amout owed for the petrol dispensed is charged to the customer's credit card account when the refueling process has finished. [...]

Now while trying to model this in a Use Case Diagram I came up with this:

foo

My main question is: Do child use cases inherit include and extend relationships? Is this valid/meaningful?

ngmir
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1 Answers1

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You are wrong here (like in the other question). Terminate is no Use Case (at best it's an anti-use case). The same goes for the other bubbles except for bill credit card. The (most likely) missing UC is Fuel car.

Generally: do NOT use generalization with UCs. It's an awful bad idea. An added value is unique (remember: it is related to unique sales proposition). You can (in 99.9% not generalize that, except you have a franchise, which is the only example that would work).

And again: Read Bittner/Spence to understand why UCs are about added value and not about functions.

qwerty_so
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  • Thank you very much for you answer. I will consider what you wrote and try to get hold of the literature. However, I do not feel like this answers my actual question: Could inheritance be used in such a way or not? – ngmir Apr 05 '18 at 07:56
  • As I said: 1) those are no use cases (lots of exclamation marks!) and 2) generalization can NOT be applied to UCs like for classes since it does not make any sense in almost all cases. – qwerty_so Apr 05 '18 at 08:36